Reproductive Behavior of Hybrid Charr (Salvelinus fontinalis × S. namaycush)

Abstract

Observations of the reproductive behavior of splake (Salvelinus fontinalis × S. namaycush) planted in Jack Lake, Algonquin Park, Ont., indicated that they spawned on rocky shoals from late October to early November. In mid-October, splake approached the spawning locations. By late October females had selected redd sites and dominant males were aggressively defending the sites that had been cleared by the females, against other males. Redd digging was variable in duration and frequency. Depth of water over redds varied between 0.5 and 4 m. No attempts were made to cover the eggs, most of which settled into the crevices between rocks. Males and females used acoustic signals during both aggression and courtship. The male initiated courtship by maintaining his head over the female's tail, then crisscrossing over the tail. Parallel positioning of the two sexes was a prerequisite to release of sex products. Visual and sonic cues appeared to be used in sequencing behavior. Circling functioned as a neutral action to which any other courting behavior could revert. Nest digging ceased after completion of egg deposition. A swim-in-place behavior of the female was a positive indicator of egg deposition. Egg predation by adult splake was observed, but it appeared to offer no serious threat to natural reproduction. Laboratory observations of splake reproductive behavior in aquaria did not indicate any behavioral obstacles to successful natural reproduction. Courtship behavior and egg deposition in the artificial spawning beds was followed by normal development and emergence of fry.Key words: splake, reproductive behavior, Ontario, visual and acoustic signaling

Lake trout (Salvelinus namaycush) spawning behaviour: the evolution of a new female strategy

“…In a study with Salvelinus fontinalis×S. namaycush hybrids, Berst et al (1981) reported that different sound frequencies were associated with distinct behaviours such as female diggings and pair spawning quiverings. Salmonids are thought to have very poor hearing-they are only Fig.…”

Observations of Spawning Behaviour in Salmoninae: Salmo, Oncorhynchus and Salvelinus

“…This idea, based on the supremacy of large dominating males in the spawning grounds, only allowed females a passive role in spawning activity. Nevertheless, females have been reported to exhibit their choice by frequently attacking smaller males (Berst et al, 1981;Keenleyside and Dupuis, 1988b;Ja¨rvi, 1990;Petersson and Ja¨rvi, 1997;Berejikian et al, 1997), and by delaying spawning when courted by nondesirable males (Schroder, 1981;Foote, 1988Foote, , 1989Foote and Larkin, 1988;Blanchfield and Ridgway, 1999;Berejikian et al, 2000;Gaudemar et al, 2000b). Delaying spawning is a form of choice by which females increase their chances of being joined by larger or more fit males.…”

“…To do so he maintains a backward position and constantly passes over her caudal peduncle from side to side trying to guard her from males coming from either side. This conduct has been called ''crossover'' (Tautz and Groot, 1975;Berst et al, 1981;Berejikian et al, 1997;Gaudemar et al, 2000b). Crossover behaviour possibly contributes to courting due to constant stimulation of the female's dorsal area (personal observations).…”

Comparative Study of Genome Divergence in Salmonids with Various Rates of Genetic Isolation

“…No information on the level of phylogenetic relationships between S. namaycush and S. fontinalis is available to us. However, existence of hybrid forms traced up to F 4 by Berst et al [66] and entering reproductive relations indicate close relations between these two North-American species. Molecular data by Westrich et al [67] also are in favor of this assumption.…”